1. Field of the Invention:
The present invention relates to a check valve having a valve positioned within a valve chamber and normally urged toward a valve seat, an inlet port and outlet port positioned at upper and lower portions of the valve chamber in which the valve is released from the valve seat by a fluid pressure for allowing the fluid to flow from the inlet port to the outlet port.
2. Description of the Prior Art:
A prior art of this type of disclosed in Japanese Utility Model Publication No. 61-21649 and will be described with reference to FIG. 3.
A prior Check valve 30 comprises an upper valve body 33 having an inlet port 32 at the upper portion thereof and a valve seat 31 at the lower portion thereof, a lower valve body 35 having an oulet port 34 at the lower portion thereof, a valve chamber 36 defined between the upper and lower valve bodies 33, 35, a movable stem 38 positioned within the valve chamber 36 and having a valve 37 which can be brought into contact with the valve seat 31, a spring 41 positioned in the valve chamber for urging the movable stem 38 for thereby permitting the valve 37 to be brought into contact with the valve seat 31, wherein the valve 37 is released from the valve seat 31 by fluid pressure for allowing the fluid to flow from the inlet port 32 to the outlet port 34. The check valve 30 further includes a damper 40 made of an elastic rubber supported by the movable stem 38 and having a plurality of damper pieces which can slide on an inner cylindrical surface 39 of the lower body 35 forming a fluid passage in the manner that the damper pieces are brought into contact with the inner cylindrical surface 39 with some frictional force.
However, according to the prior check valve there are following problems.
(1) A check valve characteristic, namely, the characteristic that the valve is released from or contacts the valve seat, is likely to be changed because of variation of elasticity of the damper and variation of frictional force of the damper against the inner cylindrical surface when an axis of the stem guide provided in the upper body 33 is displaced from the axis of the lower body 35 and the axis of the movable stem 38 to cause the damper not to come into contact properly with the inner cylindrical surface of the lower valve 35 forming the fluid passage since the check valve is not provided with an axis displacement regulation mechanism. Hence, parts of the check valve must be manufactured with high accuracy to prevent the axial displacement from occuring in the course of manufacturing said assembling the check valve.
(2) Furthermore, the check valve characteristic is also likely to be changed because of variation of elasticity of the damper and variation of frictional force of the damper against the inner cylindrical surface since the inner periphery of the damper is clamped by the movable stem 38 while the outer periphery of the damper is clamped by the inner cylindrical surface of the lower body so that the damper is restricted in its operation when the variation of elasticity of the damper and variation of frictional force of the damper against the inner cylindrical surface of the lower valve body is changed by expansion of the fluid and by environmental variation such as the variation of the temperature, and the like.
In view of the problems as set forth above, it is an object of the present invention to provide a check valve to cope with the axial displacement of the damper and the environmental variation for preventing the check valve characteristic from varying at maximum extent.
To achieve the above object, the check valve according to the present invention comprises a first valve body provided with an inlet port at the upper portion thereof for introducing fluid, a valve seat at the lower portion thereof; a second valve body having an outlet port extending downward therefrom at the lower portion thereof for discharging the fluid; a valve chamber defined by fixing the first valve body to the second valve body; a valve positioned in the valve chamber; a spring positioned in the valve chamber for allowing the valve to be brought into contact with the valve seat by the resiliency of the spring, wherein the valve is released from the valve seat by fluid pressure for allowing the fluid introduced from the inlet port to flow in the valve chamber and discharge from the outlet port; characterized in that the check valve further comprises a frustoconical projection extending upwardly from a bottom surface of the second valve body in coaxial relation with the outlet port, and an elastic member provided with a plurality of elastic pieces extending downwardly from the valve for sliding on an outer surface of the frustoconical projection in the manner to come into contact with the outer surface of the frustoconical projection.
The above and other objects, features and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.